The principle of induction melting is that a high voltage electrical source from a primary coil induces a low voltage, high current in the metal or secondary coil. Induction heating is simply a method of transferring heat energy.
The principle of induction heating is based on the following two laws:
1. Electromagnetic induction
2. The joule effect
The high frequency induction furnaces use the heat produced by eddy currents generated by a high frequency alternating field. The inductor is usually made of copper in order to limit the electric losses. Nevertheless, the inductor is in almost all cases internally water-cooled. The furnace consists of a crucible made of a suitable refractory material surrounded by a water cooled copper coil. In this furnace type, the charge is melted by heat generated from an electric arc. The coil carries the high frequency current of 500 to 2000 Hz.
The alternating magnetic field produced by the high frequency current induces powerful eddy currents in the charge resulting in very fast heating. Various configurations are available, with two or three electrodes high melting capacity (25 to 50 tons/hr) and they are used primarily for casting steel.
These currents also provide certain amount of agitation to the melting charge resulting in efficient mixing. Molten metal can be poured by tilting the furnace.
· Induction furnace does not need electrodes like electric arc furnace.
· Better control of temperature
· Better control of composition of the melt
· An induction installation usually implies a big investment that must be considered and compared to alternative heating techniques.
· Induction heating is preferably used for heating relatively simple shapes.
Materials to be casted:
· Steel alloys